Performance-Intensive Subsystems

• A computer's overall performance is directly related to how well the individual components communicate with each other. A system with a very fast processor can be hobbled by slow memory, and if its graphics are lackluster the whole system will feel slow to the user. These three subsystems, the processor, memory and graphics, are the heart of the computer system. The role of the front-side bus is to provide high-speed, efficient communications between the three.
  
  

The Roles of the Subsystems

• The three subsystems on the front-side bus are highly interdependent. The processor chip does the actual work of calculation, and carries the main load of executing instructions from the software. Because it has limited amounts of on-board memory, it must frequently send information to and from system memory as it works, in much the same way a cook removes and replaces ingredients. The results of the processor's work must then be written to the display, a job carried out by the graphics processors.
  
  

Bandwidth and Clock Speed

• There are two factors regulating the speed of data transfer. These are bandwidth and clock speed. Bandwidth is analogous to a highway at rush hour, jammed with cars: more cars can pass through an eight-lane freeway than a two-lane road. Clock speed is analogous to the speed limit on the highway. More cars can pass through in a given time, if the speed limit is 70 rather than 50. Bandwidth in computers is measured in bits, or individual pieces of data. Clock speed is measured in MHz, or frequency.
  
  

Growth in Bandwidth and Clock Speeds

• As with other factors in the performance of computers, the bandwidth and clock speeds of a computer's internal systems have increased sharply since the early 1980s when personal computers first became mainstream. Early computers could only pass data in eight-bit increments, equivalent to a single-lane road. The Intel i7 series and its contemporaries process data in 64-bit increments. Clock speeds on older systems were as low as 66 MHz, meaning they passed data through at a rate of 66 million cycles per second. As of early 2011, contemporary systems had a front-side bus speed of 1066 million cycles per second.